Covalent conjugates of small molecular weight toxins (toxic “small molecules”, MW<2,500 Daltons) to binding proteins, in particular to antibodies specific for tumor cells, are powerful tools to specifically target cancer cells for their destruction. Such antibody drug conjugates (ADCs) are of high medical and commercial interest for the therapy of cancer. In order to develop effective and safe ADCs for cancer therapy, several aspects need to be addressed: first, the antibody needs to be specific for a given tumor specific antigen (TSA), which should hardly or ideally not be expressed by normal or healthy tissue cells. Second, the covalent bond, or linkage, between the drug and the antibody/binding protein needs to be stable enough in circulation to prevent undesired release of the toxic payload in the blood stream while also effectively releasing the drug upon binding to and/or internalization into cancer cells. Third, the ADC has to be internalized in substantive quantities. Fourth, the toxic payload has to be released from the antibody and enter the appropriate cellular compartment to exert its toxicity. Fifth, the toxic payload has to be of high enough toxicity, or potency, in order to cause destruction of cancer cells, even if potentially limited amounts of the TSA are expressed on the cancer cells and therefore only limited amounts of the ADC are internalized, or if release of the toxic payload is not undertaken with high enough efficiency upon binding to the cancer cells, or upon internalization into the cancer cell.
However, equally, ADC's must also avoid inducement of side effects, generally mediated through (a) on-target binding in non-target tissues due to expression of the TSA on healthy cells, (b) off-target binding, due to binding of antigens besides the intended TSA, and/or (c) general toxicity, which may be caused by premature drug payload release in the bloodstream, released payload from lysed target cells or released metabolites.
These multiple constraints on ADC development make this type of therapeutic among the most challenging to bring through clinical evaluation. Moreover, because of the high costs of making and testing such biologic-based products, the skilled person is not at liberty to systematically test all possible variants and combinations of antibodies, linkers and toxins, as well as the particular conjugation site(s) and ratio of toxin to antibody.
Indeed, the literature reports on a multitude of possible toxin payloads and linkers (see for example Jain et al., 2015), and moreover, on a multitude of possible conjugation sites and conjugation methods.
In “Location Matters: Site of Conjugation Modulates Stability and Pharmacokinetics of Antibody Drug Conjugates” (Strop et al., Chemistry & Biology, 20, 2013), the authors report on ADCs conjugated by microbial transglutaminases. MMAD toxins conjugated to their antibody heavy and light chain C-termini presented similar efficacies both in vivo and in vitro. Doses of 10 and 25 mg/kg of ADC were equally well tolerated in rats.
The Applicant has surprisingly found that ADCs bearing anthracycline toxins bound at one or more specific sites, namely exclusively on the C-termini of one or both antibody (or antibody derivative) light chains, are not only therapeutically effective but, remarkably, are more highly tolerated in vivo than comparable ADCs with anthracycline toxins bound at alternative sites, i.e., on the C-termini of one or both antibody heavy chains or on a combination of the C-termini of the antibody heavy and light chains Such a teaching is nowhere found in WO 2016/150564 (the contents of which are incorporated herein by reference), which refers to toxins in the same class but only to their attachment to a combination of the C-termini of the antibody heavy and light chains.
Teachings referring to means of toxin attachment of antibody C-termini, namely in WO 2014/140317 (the contents of which are incorporated herein by reference), also make no reference to preferential attachment of anthracycline toxins to the light-chain C-termini.
It is hence an object of the present invention to provide an antibody drug conjugate (ADC) that presents improved properties in vivo, and in particular is highly tolerated in vivo. In particular, it is an object of the present invention to provide an antibody drug conjugate that is better tolerated in vivo than its counterpart comprising the same number of the same toxins but attached to alternative C-termini.
It is another object of the present invention to provide a pharmaceutical composition comprising such an antibody drug conjugate.
It is another object of the present invention to provide a method of making such an antibody drug conjugate.
It is another object of the present invention to provide an antibody drug conjugate for use in the treatment of a subject that is suffering from, at risk of developing, and/or diagnosed with a neoplastic disease.
It is another object of the present invention to provide an antibody drug conjugate for use in the treatment of a subject that is suffering from, at risk of developing, and/or diagnosed with an immune disease or disorder.
These and further objects are met with methods and means according to the independent claims of the present invention. The dependent claims are related to specific embodiments.